That was my usual 'trick'.Not to mention you can modify times of the advanced ones once you scan in at the first one.....
After getting the big E-Tickets at 60+ days by staying at a Disney resort, I'd try to move them all to as early in the morning as possible. But, because of the 1 hour window for each, they were spread apart in time.
After tapping into the first FP of the day, then that FP sort of 'disappeared' from schedule. So, while in queue, a little refreshing got the next FP moved to as soon as possible. Often by the time we finished the current ride, the next FP was active, allowing us to just walk over and onto that ride.
Then in that queue, a little refreshing moved the 3rd FP to as soon as possible. This allowed us to do 3 FP rides in just 90 minutes.
Tapping into the 3rd ride allowed us to grab a new FP, to happen as soon as possible. And so on, for the rest of the day.
None of that was secret information. It was oft mentioned on 'tips' websites.
I'm guessing some of the FPs that opened up and found through refreshing was because of people missing their FP window (or moving or cancelling their FP).
It was odd how FPs were available when you wouldn't think they would be. E.g., in the early evening at EPCOT, SSE would have have standby wait time for 20-30 minutes, while, at the same time, FPs for it were immediately available. Or even if the FP was for 15 minutes later, by the time we walked over to SSE the 5 minute pre-time grace period was active, and we just walked on... past a crowd that had a half hour wait.
FP greatly benefited those who knew its ins and out to the detriment, I guess, of those who didn't even bother with it.